Current mode sense amplifiers have been used in integrated circuits to sense and/or amplify differential input currents. In applications in semiconductor memory, for example, the current mode sense amplifiers are often used to sense and amplify input currents resulting from reading memory cell data and being provided over relatively long signal lines.
In providing memory cell data, signal lines may be precharged to a supply voltage VCC. Depending on the application and/or design of a semiconductor memory, the supply voltage VCC of the memory may have a relatively small or large magnitude relative to other implementations.
Typically, differential input currents received from memory are voltage dependent on the supply voltage VCC. For example, the input currents and VCC may be linearly proportional to one another. As a result of increasing VCC, the input currents may increase as well.
As known the supply voltage VCC may fluctuate, varying over a range of voltages during operation. Where VCC is at a lower end of the range, input currents typically are very weak and low in magnitude. The differential input currents received from the memory may have low signal margins, and performance issues, such as data read errors, may result. On the other hand, where the VCC is at a higher end of the range, the differential current may exceed what is required to properly sense memory cell data. Consequently, in reading data out of memory, power may be needlessly consumed. Therefore, there is a need for a more reliable and efficient apparatus for sensing read data, for example, from a memory array despite variations in supply voltage.